Setup cannot continue because this version  of the .NET Framework is incompatible with a previously installed  one.

Description: When you try to install the Microsoft .NET Framework 2.0 on a computer that has the .NET Framework 2.0 Service Pack 1 installed, you may receive an error  message that resembles the following:
Setup cannot continue because this version of the .NET Framework is incompatible with a previously installed one.

Cause: The .NET Framework 2.0 Service Pack 1 is a later version of the .NET Framework 2.0. The earlier version cannot be installed over the later version.

Solution: Uinstall the .NET Framework 2.0 Service Pack 1 before you install the .NET Framework 2.0.